The present invention relates to a suspension system for automotive vehicles, and more particularly to an improvement of a double wishbone type suspension, a strut type suspension, and the like.
Such a conventional suspension system as described above comprises a longitudinal shaft fixedly mounted on a vehicle body structure along the fore-and-aft axis of the vehicle, a control arm of the so-called "A" type swingably supported at one end thereof from the longitudinal shaft by means of a pair of front and rear rubber bushes and having a swingable end supporting thereon a road wheel, and a pair of retainer plates fixed to front and rear ends of the shaft and being arranged to receive a load acting on the control arm in the forward or rearward direction through a portion of the respective rubber bushes for restricting forward or rearward displacement of the control arm.
In the case that the control arm is adapted as an upper control arm in the suspension system, the upper control arm will receive a heavy load acting thereon in the forward direction due to braking force of the vehicle or shocks from the road in traveling of the vehicle. In the case that the control arm is adapted as a lower control arm in the suspension system, the lower control arm will receive a heavy load acting thereon in the rearward direction due to braking force of the vehicle or shocks from the road in traveling of the vehicle. This is caused by the fact that the maximum load acting on the control arm in forward traveling of the vehicle is extremely larger than that in backward traveling of the vehicle. When a heavy load acts on the control arm in the forward or rearward direction, one of the retainer plates concentrically receives the heavy load through one of the rubber bushes, and the reaction force from the retainer plate is given to the front or rear portion of the control arm. For this reason, sufficient strength of the rubber bushes, retainer plates, and control arm is required to resist the heavy load and reaction force. This means that the assembly of the rubber bushes, retainer plates and control arm becomes larger in size and causes an obstacle to a small size and light weight construction of the suspension system.